gonadotropin go·nad·o·tro·pin (gō-nād'ə-trō'pĭn, -trŏp'ĭn) or go·nad·o·tro·phin (-trō'fĭn, -trō'pĭn)n. A hormone that stimulates the growth and activity of the gonads, especially any of several pituitary hormones that stimulate the function of the ovaries and testes. Also called gonadotropic hormone.